Brown has continued to enjoy a high public profile since losing his reelection bid last year and announcing he would not seek the seat that opened when John Kerry became secretary of state. Last month, he joined a Boston law firm and has popped up intermittently on Fox News, where he is a contributor.

Reached via cellphone in what he said a producer’s meeting, Brown said he was “excited” for his turn on O’Reilly’s show, which commanded the highest ratings on cable news television in February.